1. Field of the Invention
This invention relates to a method for preventing or damping vibrations and noise in a vehicle, particularly in an automobile.
2. Description of the Prior Art
The vibrations or noise in a vehicle is one of the major factors which impair comfortable riding in a vehicle. In general, the rotation of an engine or vibrations of a vehicle during its running are transmitted to a vehicle body and then vibrate the walls of a vehicle body, resulting in the generation of noise in the passenger compartment in the vehicle. Many attempts have been proposed to overcome the vibration and noise problems experienced with a motor vehicle. It is known that the noise or sound may be damped to a considerable extent according to the vibration-damping action of vibration-proof materials or buffer materials, such as a rubber cushion, insulator and the like, which are used in respective appropriate portions of a vehicle. These include engine mounts, body mounts and suspension systems. However, the sound-damping or insulating actions of these vibration-proof materials are dependent upon their individual sound-damping or insulating effects alone. In addition, many attempts have been proposed to improve the characteristics of individual vibration-proof materials as well as to increase the number of vibration-proof materials. However, the resulting sound-insulating or damping effects of these vibration-proof materials remain only no more than the sum of the individual effects of these vibration-proof materials.
Meanwhile, difficulties have been confronted with the concept of improvements in individual vibration-proof materials, and in addition, the use of an increased number of vibration-proof materials is not desirable from viewpoints of drivability and stability of a vehicle, thus resulting in only a partial success in damping or insulating sound or noise.